The invention relates to polycrystalline diamond (PCD) composite compacts comprising a PCD structure bonded to a substrate, method for making same, tools incorporating same and method for the making tools.
Polycrystalline diamond (PCD) is a super-hard, also called superabrasive material comprising a plurality of substantially inter-grown diamond grains, forming a skeletal mass defining interstices between the diamond grains. PCD is distinguished from composite materials and tool components comprising substantially non-inter-grown diamond grains dispersed within a supporting matrix. As used herein, PCD material comprises at least 80 volume percent, or even at least about 85, volume percent diamond and may be made by subjecting an aggregated mass of diamond grains in the presence of a sintering aid, such as cobalt, to an ultra-high pressure of greater than about 5, GPa, for example, and temperature of at least about 1,200 degrees centigrade, for example. The sintering aid, also known as solvent/catalyst material or catalyst material for diamond, may promote the inter-growth of diamond grains. PCD material may be sintered and integrally formed onto a substrate body comprising cobalt-cemented tungsten carbide, which may provide a source of cobalt for sintering the diamond grains, to form a PCD composite compact. A PCD structure thus joined to a substrate may be said to be “integrally bonded” to the substrate. Materials that do not promote substantial coherent intergrowth between the diamond grains may themselves form strong bonds with diamond grains, but are not suitable catalyst materials for sintering PCD materials.
PCD material is used in a wide variety of tools for cutting, machining, drilling or degrading hard or abrasive materials such as rock, metal, ceramics, composites and wood-containing materials. For example, PCD elements comprising PCD composite compacts are used as cutting elements on drill bits used for boring into the earth in the oil and gas drilling industry. PCD elements are also used for machining and milling metal-containing bodies, such as may be used in the auto manufacturing industry.
The composition of PCD material may be selected depending on the intended application and the nature of the body to be machined, cut, drilled or degraded. One aspect of the composition that may affect key properties and behaviour of PCD material is the mean size of the diamond grains comprised in the PCD material, which may influence certain mechanical and other properties and consequently the performance of the PCD in use and the ease with which a tool comprising the PCD material can be re-sharpened. PCD materials comprising diamond grains having a mean size of several microns may be particularly difficult to cut and grind.
U.S. Pat. No. 3,745,623, discloses the application of high pressure, high temperature technology to provide diamond tipped machine tools in which in place of utilizing a single diamond, the working diamond content is present in the form of a mass of diamond crystals bonded to each other.
U.S. Pat. No. 4,303,442, discloses a diamond sintered body and a method for producing the same, wherein a mixture comprising 50-95 volume percent of a diamond powder below micron, the remainder consisting of a powder below 1, micron of one or more than two kinds of carbides, nitrides, borides of IVa, Va and VIa group metals of the periodic table and solid solutions thereof, and further a powder of iron group metals, is interposed between a plurality of cemented carbide plates, and then subjected to hot press sintering at a high temperature and high pressure under which diamond is stable thereby enabling to obtain a diamond sintered body having high wear resistance.
Japan patent publication number 09-316587A discloses a high strength fine particle diamond sintered body, in which the grain size of the diamond particles is in the range of between 0.1, and 4, microns, and comprising a bonding material containing at least 1, iron group metal chosen from the group consisting of Fe, Co and Ni, and at least one of the metallic carbide, nitride or boride compounds which are chosen from the 4A, 5A and 6A periodic table groups and a solid solution or mixture of these.
PCT publication number WO/2008/053430, discloses a method for making PCD composite material, the method including introducing finely particulate tungsten carbide particles, having a preferred size of less than 1, micrometer.
European patent application publication number 0 976 444, discloses a PCD structure comprising a mass of diamond grains having a size in the range from 1, to 10, microns. A thin PCD layer sintered between two cemented carbide discs, each having a thickness of 3, mm and comprising 4, weight percent to 6, weight percent Co, is also disclosed.
International application publication number WO/2007/020518, discloses a polycrystalline diamond abrasive element comprising a fine grained polycrystalline diamond material and a second phase comprising catalyst/solvent for the diamond material, wherein the polycrystalline diamond material is characterised in that it has an average catalyst/solvent mean-free-path value of less than 0.60, micron, and a standard error for the catalyst/solvent mean-free-path that is less than 0.90, micron.
There is a need to provide PCD composite compacts, particularly but not exclusively comprising high strength grades of PCD material or very fine-grained PCD material, which are easier to cut and grind, and tool components comprising same.